As one example of a solenoid valve for operating a valve element by a solenoid, a directional control valve for controlling an air flowing direction is known. As this directional control valve, an opening/closing valve for opening and closing a flow channel by the valve element, a switching valve for switching a flow channel, and the like are known. Supply and interruption of supplying of compressed air to a pneumatic circuit are controlled by the opening and closing valve, and a supplying direction of the compressed air is controlled by the switching valve. The solenoid valve has an electromagnet, i.e., a solenoid incorporated in a resin case and provided with a fixed iron core and a coil wound on the fixed iron core, and a valve body in which a movable element, i.e., an armature operating a valve element is incorporated, and the movable element is driven by the solenoid.
When the valve element is operated by the solenoid, an exposed surface of the fixed iron core serves as a magnetically-attracting surface for attracting an object by a magnetic force, so that the movable element is moved toward the magnetically-attracting surface. When the movable element is made to collide against a magnetically-attracting surface directly, a tendency in which the movable element sticks to the magnetically-attracting surface may become high, and it may become difficult for the movable element to be separated from the magnetically-attracting surface. Therefore, when a turning-on operation of the valve element is carried out against a spring force by supplying an electric current into the coil, and after that, a turning-off operation of the valve element is carried out by stopping the electric current, the response characteristics of the turning-off operation is decreased.
In order to improve the characteristics, a solenoid valve described in Patent Document 1 is provided with a nonmagnetic material film on a magnetically-attracting surface of a fixed iron core, a movable element is provided so as to abut on the fixed iron core via the nonmagnetic material film. In a solenoid valve described in Patent Document 2, a cushion having an abutting surface which protrudes in comparison with a magnetically-attracting surface of a fixed iron core is provided at a tip of the fixed iron core, and a movable element is provided so as to abut on the cushion without abutting on the magnetically-attracting surface. In a solenoid valve described in Patent Document 3, a magnetically-attracting surface of a fixed iron core is flush with a bottom surface of a bottom member, and when a movable element collides with the magnetically-attracting surface, an impact of the movable element to the magnetically-attracting surface is absorbed.